Alpha-(p-hydroxyphenyl) cumic acids and esters

ABSTRACT

THIS INVENTION RELATES TO A NOVEL CLASS OF HYDROXY SUBSTITUTED AROMATIC ACIDS WHICH INCLUDES ALPHA-(HYDROXYPHENYL) CUMIC ACID AND SUBSTITUTED DERIVATIVES THEREOF. THESE HYDROXY SUBSTITUTED AROMATIC ACIDS CAN BE EMPLOYED AS STARTING MATERIALS IN THE PREPARATION OF USEFUL POLYESTERS.

Feb. 1, 1972 B C OxENRmER ETAL 3,639,464

ALPHA(PHYDROXYPHENYL) CUMIC ACIDS AND ESTERS 2 Sheets-Sheet 1 OriginalFiled Aug. 17, 1964 JJDI 20md 0 OJ I wmDJOmODJu UIP 0.-. NDOWZ MLZOTPm1OM0 J0 m. .mw n.. N.. o. m o u n v m N j .n n V nu- Q 4 .W n ...nc. l 3 ho mm u -3 ...3 umd .n-o

Feb, 1. 1972 B. c. oxENRlDER ETP-L ALPHA-(P-HYDROXYPHENYL) CUMIC ACIDSAND ESTERS Original Filed Aug. 17, 1964 2 Sheets-Sheet 2 l llllll .NGE

BDNVQHOSQV lUnited States Patent Office 3,639,464 Patented Feb. 1, 19723,639,464 ALPHA-(p-HYDROXYPHENYL) CUMIC ACIDS AND ESTERS Bryce C.Oxenrider, Florham Park, and Morton H. Litt and Ferdinand M. Slavik,Morristown, NJ., assignors to Allied Chemical Corporation, New York,N.Y. Original application Aug. 17, 1964, Ser. No. 389,849, now PatentNo. 3,398,121, dated Aug. 20, 1968. Divided and this application Mar.19, 1968, Ser. No. 735,942 Int. Cl. C07c 65/14 U.S. Cl. 260-520 2 ClaimsABSTRACT OF THE DISCLOSURE This invention relates to a novel class ofhydroxy substituted aromatic acids which includes alpha-(hydroxyphenyl)cumic acid and substituted derivatives thereof. These hydroxysubstituted aromatic acids can be employed as starting materials in thepreparation of useful polyesters.

This is a division of application Ser. No. 389,849 iiled Aug. 17, 1964,now Patent No. 3,398,121.

The hydroxy substituted aromatic acids and derivatives thereof of thepresent invention are compounds of the formula:

wherein X is a member selected from the group consisting of alkylradicals having from 1 to 4 carbon atoms, chlorine and bromine, M ishydroxyl or a substituent hydrolyzable thereto and n is an integer fromto 4. Hydrolyzable substituents to the hydroxyl group include loweralkoxy groups e.g. the methyl ester, and the like. These compounds areuseful as intermediates in the preparation of new polymeric materials aswill be further illustrated herein. These compounds can be prepared bythe condensation reaction of a monohydric phenol compound with an alphasubstituted derivative of cumic acid or a compound hydrolyzable theretoas illustrated in the following equation.

wherein X and n have the meanings given above, the phenolic compoundhaving a substitutable hydrogen atom present at the position para to thehydroxy substituent and Y is a member selected from the group consistingof hydroxy, bromine and chlorine, M having the meaning given above. y

The reaction between iat-substituted cumic acid or hydrolyzablederivative thereto and the phenolic compound is preferably carried outin an inert solvent medium using an equal molar ratio of reactants or anexcess of either reactant. We prefer, however, to obtain a liquidreaction medium simply by using an excess of the phenolic compound andconducting the reaction above the melting point of the phenoliccompound. Use of an excess of phenolic compound rather than an excess ofthe -substituted cumic acid or hydrolyzable derivative minimizes theformation of side products which result when a-sub- O -C-M HY stitutedcumic acid or derivative hydrolyzable thereto reacts `with the ring vofthe phenolic compound at more than one position. For the sake of clarityand brevity, it is to be understood that the term cumic acid or relatedterms includes compounds hydrolyzable thereto as above set forth.

We have found in our reaction that when Y is bromine or chlorine, thatthe reaction liberates HCl or HBr as the case may be which acids areparticularly appreciated as reaction products in that they increase thereaction rate of the phenolic compound with the zia-substituted cumicacid. Hence, in our reaction we can, if desired, employ HCl or HBr ascatalysts for the reaction, or employ achlorocumic acid or a-bromocumicacid as the reactant, in which case, addition of catalyst is notnecessary.

This reaction is conducted above the melting point of the phenoliccompound and up to and including its reflux temperature. Temperaturesbetween about 45 and 180 C. are used in the case of phenol which meltsat about 42 C. and reuxes at about 182 C. at atmospheric pressure.

The use of a substituted phenol having one or more substituents selectedfrom the group consisting of alkyl radicals of l to 4 carbon atoms,chlorine and bromine at one or more of the ortho and/or meta positionsresults in a product having -corresponding substitution on thehydroxyphenyl group. For instance, the use of o-cresol givesa-(3-methyl-4-hydroxyphenyl) cumic acid; 2,6- xylenol givesa-(3,5-dimethyl-4-hydroxyphenyl) cumic acid, lwhile the use ofo-bromophenol gives a-(S-bromo- 4-hydroxyphenyl) cumic acid whenfollowing the manipulative procedure set forth in Example 1 herein.Alternatively, a chlorine or bromine substituted hydroxyphenyl cumicacid can be obtained by vfirst obtaining a-(p-hydroxyphenyl) cumic acidby reaction of phenol with say, a-bromo-cumic acid and thenpost-chlorinating or postbrominating the product by conventional means,whereby the hydroxy substituent on the hydroxyphenyl group directssubstitution of the halide atom to the ring of the hydroxyphenyl group.To prepare the a-substituted cumic acid reactant, a-hydroxycumic acid isprepared by the oxidation of cumic acid with KMnO4, 'while a-chlorocumicacid `and a-bromocumic acid are prepared by reaction of cumic acid withchlorine and bromine, respectively. Compounds hydrolyzable to cumic acidcan be prepared by conventional methods and can be reacted as above toprepare the a-substituted cumic acid reactant,

In order to illustrate the preparation of the new a- (hydroxyphenyl)cumic acid, compound the following examples are presented.

EXAMPLE 1 240 grams of phenol were placed in a reaction vessel equippedwith a gas inlet tube, stirring means, a thermometer and a condenser.The phenol was heated to 50 C. i.e., about 9 C., above its melting pointand HC1 gas was bubbled through the phenol until it became saturated asindicated by the phenol becoming straw colored. 50 grams ofa-chlorocumic acid were added and the reaction was run at about 51 C.for 1% hours.

At completion of the reaction, the HC1 which remained was removed byadding cc. benzene to the reaction mixture and then distilling off thebenzene. The phenol was then removed by distillation at a reducedpressure at about 12 mm. The distillation was stopped when the pottemperature reached C. and the product was then purified by successiverecrystallizations from toluene giving 15.5 grams of a pale tan solidmelting at 170.5- 172.5 C. This product was confirmed to be.a-(p-hydroxyphenyl) cumic acid by infrared absorption spectroscopy andelemental analysis. The elemental analysis was as follows:

Theoretical (percent): C, 74.98; H, 6.29; O, 18.73. Found (percent): C,74.60; H, 6.22; O, 19.18.

The infrared absorption spectrogram obtained using a Perkin-Elmerabsorption spectrometer Model 21, MaCl prisms and a split mull is shownin FIG. 1. The absorp- .tion peak at 3.0 microns indicates presence of aphenolic OH group in the compound while the peak at 3.4 micronsindicates presence of alkyl groups; the peak at 5.9 microns indicatespresence of a carboxyl group of an acid attached directly to an aromaticgroup, the peaks at 6.2 microns and 6.35 microns indicate presence ofaromatic groups as does the peak at 6.6 microns. The absorption peak at6.8 microns indicates presence of an alkyl group and the peaks at 7.2and 7.4 microns are believed to be due to gem di-methyl groups i.e. 2methyl groups on a single carbon atom. The peak at 12.05 micronsindicates para substitution.

EXAMPLE 2 130 grams of phenol were placed in the same reaction vessel asused in Example 1. The phenol was heated to 50 C. and saturated withHC1. 24 grams of zx-hydroxycumic acid were added and the reaction wasrun for four hours with HC1 being added during the first fortyfiveminutes.

At the completion of the reactions, the HCl which remained was removedby adding 100 cc. of benzene to the reaction mixture and then distillingoff the benzene. The phenol was then removed by distillation at areduced pressure of about 12 mm. The distillation was stopped lat atemperature of 125 C. and ,100 cc. of toluene was added, resulting inthe precipitation of a tan solid. After recrystallization from 265 cc.of toluene, 16.8 grams of product melting at 169.5-171 C. were obtained.This product was confirmed to be a-(p-hydroxyphenyl) cumic acid byelemental analysis. The elemental analysis was as follows:

Found (percent): C, 74.82; H, 6.29; O, 18.89.

EXAMPLE 3 164 grams of cumic acid and 900 cc. of carbon tetrachloridewere charged into a 2 liter flask fitted with an agitator, condenser anda dropping funnel and irradiated by a sun lamp positioned 1/2 inch fromthe bottom of the flask. The reaction mixture was warmed to 30 C. andthe sun lamp turned on. A solution of 160 grams of bromine in 100 cc. ofcarbon tetrachloride was added dropwise to the reaction mixture over aperiod of 3 hours until all but 4 grams of the bromine had been added,at which time an excess of bromine was present in the reaction mixture.The reaction mixture was cooled to C. and the resulting precipitaterecovered by filtration. After washing this precipitate with 300 cc. ofcold carbon tetrachloride there was obtained 220 grams of oc-bromocumicacid having a melting point of 160 C.

2116 grams of the aebromocumic acid were mixed with 1 liter of phenoland heated at 60 to '70 C. for two hours and then at 125 C. for onehour. The reaction mixture was cooled to 50 C. and 1 liter of benzeneadded. HBr was removed by washing with two 200 cc. quantities of -waterfollowing which the reaction mixture was extracted three times with atotal of 52.58 grams of NHrOH in an aqueous solution containing 10% byWeight NH4OH. The extracts were neutralized with 10% sulfurie acidalthough any mineral acid can be used for the neutralization. Uponneutralization of the extracts, a precipitate formed which Was recoveredby filtration. The product thus obtained was 66 grams ofa-(p-hydroxyphenyl) cumic acid having a melting point of 165 to y170 C.The benzene layer was then distilled first at atmospheric pressure toremove benzene and then at 4 mm. pressure up to a temperature of 125 C.to remove unreacted phenol. A dark purple viscous oil remained after thedistillation which was hydrolyzed with hot NaOH and then neutralizedwith 19% H2304- A dark Oil was produced which precipitated upon waterextraction. After water washing and drying this precipitate there wasobtained an additional 106 grams of a- (p-hydroxyphenyl) cumic acid.

As indicated above, these new compounds are useful in the production ofmonomers of new polyesters. These monomers are prepared by theesterifcation which is illustrated by the following equations:

wherein R is an alkyl radical of 1 to 18 carbon atoms and X, n and IMhave the meanings given above for the a- (hydroxyphenyl) cumic acid. Theesterification reaction is preferably carried out in an inert solventsuch as pyridine at temperatures between about 25 C. and 150 C.Temperatures below 25 C. cause the reaction rate to be substantiallydecreased and the production of the ester nneconomical. When pyridine ora similar compound is used as the inert solvent, the reaction isconveniently conducted at the reflux temperature of the reaction medium.The molar ratio in the reactants in the esterication is not critical andan excess of either reactant can be employed to drive the reactant tocompletion, or, although not desirable, stoichiometric amounts ofanhydride can be employed relative to the a-(hydroxyphenyl) cumic acid.Preferably, an excess of the acid anhydride is employed with about 1.1to 5 mols of anhydride being used per -mol of the a-(hydroxyphenyl)cumic acid compound. When an excess of acid anhydride is employed themonomer can be conveniently recovered by hydrolyzing the excessanhydride with water, thereby causing the monomer to precipitate.Purification of the monomer can be effected by recrystallization from asolvent such as toluene. In order to illustrate the preparation of thenew ester compounds such as a-(p-acetoxyphenyl) cumic acid the followingexample is set forth:

EXAMPLE 4 2 grams of a-(p-hydroxyphenyl) cumic acid, 2.16 grams aceticanhydride and 10 ml. pyridine were heated in a steam bath for one hour.The solution was then cooled in ice for one half hour, following whichit was poured into 50 ml. of water and stirred for three hours tohydrolyze the excess acetic acid. Upon hydrolysis, a solid precipitatedwhich was filtered, washed with water and then dried. The resultingwhite solid was purified by recrystallization from toluene and a yieldof product having a melting point of ll-162 C. was obtained. Thestructure of the compound was confirmed to be a- (p-acetoxyphenyl) cumicacid by infrared absorption spectroscopy and nuclear magnetic resonance.Elemental analysis of the product was as follows:

Theoretical (percent): C, 72.47; H, 6.08. Found (percent): C, 72.15; H,6.15.

The spectrum was obtained in CD'C13 (D representing deuterium) for thenuclear magnetic resonance tests. Chemical shifts for the various typesof protons are illustrated in parts per million from tetramethyl silanein the following table:

p.p.m. (of magnetic field strength) (a) 7.20 and 7.33 (fb) 7.90 and 8.03(c) 7.06 and 7.20 (d) 6.83 and 6.97 (e) 2.24

The apparatus employed was a Varian A-60 nuclear magnetic resonancespectrometer ('60 megacycles).

The infrared absorption spectrogram of the compound which spectrogramwas obtained using a PerkinElmer absorption spectrometer Model 21, NaClprisms and a split mull is shown in FIG. 2. The absorption peaks at 3.3and 3.4 microns indicate presence in the compound of an aliphatic group-while the absence of a peak at 3.0 microns indicates absence of thephenolic OH group present in a-(p-hydroxyphenyl) cumic acid. The peak at5.7 microns indicates presence of an acetoxy group While the peak at 5.9microns is due to the presence 'of a CIO group of an acid attacheddirectly to an aromatic ring in the compound. Peaks at 6.2 and l6.6microns are due to the presence of aromatic bonds in the compound Awhilethe peak at about 7.2 microns indicates methyl group absorption. Thepeak at about 11.7 microns indicates para substitution.

By substituting, in place of the a-(p-hydroxyphenyl) cumic acid ofExample 1, a-(3-bromo-4-hydroxyphenyl) cumic acid there is obtained uponthe reaction with acetic anhydride (3-bromo-4-acetoxyphenyl) cumic acidwhen following the procedure of Example 4. Likewise, whena-(3-methyl-4-hydroxyphenyl) cumic acid is reacted in the manner ofExample 4 with acetic anhydride there is obtaineda-(3-methyl-4-acetoxyphenyl) cumic acid and whena-(3-chloro-4-hydroxyphenyl) cumic acid is reacted following the samemanipulative procedure of Example 4, there is obtained the correspondingsubstituted a-(phydroxyphenyl) cumic acid i.e.,a-(3-chloro-4-acetoxyphenyl) cumic acid.

The polyesters which can be produced by polymerizing the alkyl esters,we have found, possess high glass transition temperatures and because ofthis particular property the polyester polymers are particularly usefulin heat resistant lrns and fibers. This is considered a significantadvance over prior art polyesters produced by the reaction ofdifunctional acids or their ester derivatives with dihydric alcohols.These polyesters are generally characterized by low glass transitiontemperatures of about 50 to 100 C. making them unsuitable for hightemperature applications.

The polyester polymers of this invention are composed of recurring unitsof the formula:

wherein X and n have the meanings given above with respect to thehydroxyphenyl cumic acids and esters of alkyl acids. The polyesterpolymers of this invention are prepared by the polymerization of theabove ester intermediates in the presence of a catalyst whichpolymerizes diesters with glycols. These catalysts are a known class;they are generally selected from the group consisting of Group V metaloxides, sodium alkoxytitanates, tetraalkyltitanate esters, alkalineearth salts of weak acids and metallic magnesium. Optimum results in thepolymerization of the ester intermediates are obtained using metallicmagnesium as the catalyst. Metallic magnesium is further preferredbecause some of the organic metallic compounds above mentioned areconsiderably more expensive than metallic magnesium.

The temperature of the polymerization is above the melting point of themonomer and the reaction is terminated above the flow point of thepolymer. Generally, and especially in the case where a-(p-acetoxyphenyl)cumic acid is polymerized, the temperature of the polymerization will bein the range of 165 to 400 C. During the reaction, acid is formed as aside product and vaporizes and can be removed from the system. Sincethis acid is undesirable in the reaction medium it is preferred tooperate the polymerization under conditions which will readily vaporizethe acid and remove it from the reaction medium. Such conditions includeuse of reduced pressures. Since the reaction mixture becomes moreviscous as the reaction proceeds, the pressure in the system can beprogressively reduced to aid in the removal of the acid vapors.

Our polymerization is preferably performed in an inert atmosphere and inthe absence of water since air or substantial atmospheric moisture canhave some deleterious effect upon the reaction or the products obtainedthereby. This is especially true when the reaction is performed athigher temperatures, say temperatures substantially above the flow pointof the resultant polymer.

Our new polyester polymers have, as indicated above, high glasstransition temperatures which in the case of polymers produced froma-(p-acetoxyphenyl) cumic acid are over 200 C. These high transitiontemperatures of the polymer make them very useful as heat resistantlilms and bers. The polymers are soluble in m-cresol, sym.tetrachloroethane and o-dichlorobenzene and thus can be processed byusing a solution of the polyester in one of these solvents. The termglass transition temperature of the polyester resin as used herein,refers to a second order transition temperature which can be determinedby plotting the apparent modulus of rigidity of a sample as a functionof temperature and can be deiined as the temperature at which theapparent modulus of rigidity of the sample possesses a value of1.45)(104 p.s.i.g. This determination can be made in accordance withASTM test D1043-61T.

Polymers of a-(p-acetoxyphenyl) cumic acid according to our inventioncan have a Wide range of molecular weights as determined by inherentviscosity. Where reference is made herein to inherent viscosity, it isdetermined by iirst determining the relative viscosity in an OstwaldViscometer tube on .5 gram of polymer in a ml. solution of m-cresol at30 C. and the inherent viscosity is reported in deciliters per gram(dL/g). Generally, polymers having an inherent viscosity between .5dl./g. and 2 dL/g. are particularly useful. Polymers ofa-(p-acetoxyphenyl) cumic acid with an inherent viscosity between .75dl./g. and 2 dl./g. can be spun into fibers using either solventspinning methods or melt spinning methods. In the case of solventspinning the iiber, either the wet spinning or so-called dry orevaporative spinning method can be suitably employed. Suitable solventsof the polymer include m-cresol, sym. tetrachloroethane ando-dichlorobenzene and when wet spun, the fibers can be formed in a nonsolvent of the polymer but a solvent of the spinning solution. Theiibers are highly heat resistant due to their high glass transitiontemperature, about 200 C. and higher. Polymers of a-(p-acetoxyphenyl)cumic acid having an inherent viscosity between .5 dL/g. and l dl./g.are capable of being molded by conventional molding operations intoproducts having a high dimensional stability up to temperatures of about218 C.

In order to illustrate a method of preparing our new polyester polymersproduced from the new ester intermediates such as a-(p-acetoxyphenyl)cumic acid the following example is presented.

EXAMPLE 5 To a 100 ml. capacity resin pot equipped with heating andstirring means and kept under nitrogen atmosphere, were added 30 gramsof a-(p-acetoxyphenyl) cumic acid and .003 gram of metallic magnesium.The charge was reacted over a iive hour period employing the followingpressure-temperature-time cycle:

Time Pressure Temperature (hours) (mm. Hg.) C.)

Acetic acid was removed as the reaction by-product during the course ofthe reaction, due to the decrease in the pressure over the reactionperiod. At the end of ve hours the reaction mixture was cooled to roomtemperature under nitrogen atmosphere and the caramel colored mass wasdissolved in 500 ml. of tetrachloroethane. The polymer solution waswashed with 2% HCl and then with 100 ml. portions of deionized water toremove residual HCI. After ltering the solution the polymer wasprecipitated by adding the solution to 3 liters of acetone whilestirring. The mother liquor was decanted and the `residualtetrachloroethane was extracted from the precipitate with acetone. Thepolymer was dried overnight in a vacuum oven at 60 C. under reducedpressure of the 2 mm. Hg.

16 grams of polymer were recovered and the inherent viscosity of thepolymer was determined to be 0.76 deciliter per gram. The inherentviscosity was determined as a'bove.'The polymer was olf-white in colorand had a number average molecular Weight of 11,800 as determined on aMechrolab Vapor Pressure Osmometer Model 302 at 130 C. in 1.0 and 1.7%solutions in dichlorobenzene. The glass transition temperature of thepolymer determined as above outlined using ASTM test B1043- 61T was 218C.

The ow point of the polymer was determined to be in the range of 285 to300 C. The ow point was determined by placing a sample of the polymer ina hotstage microscope, i.e. a microscope mounted on top of a heatingmantle, and subjecting the polymer to gradually increassing heat untilit was noted through the microscope that the sample started to ow. Atthat point, the polymer had reached its ilow point.

In accordance with the above procedure and Example 5 there can beprepared polymers of the alkyl ester wherein the phenyl substituent ofthe cumic acid compound has an additional ring substituent. Forinstance, poly at-(3- bromo 4 acetoxyphenyl) cumic acid; polya-(3-chloro- 4-propoxyphenyl) cumic acid from (3 chloro4pro poxyphenyl)cumic acid or poly a-(3-methyl 4 acetoxyphenyl) cumic acid froma-(S-methyl 4 acetoxyphenyl) cumic acid or copolymers can 'be preparedfrom mixtures of the above or similar monomers. Moreover, the monomersof this invention can be copolymerized with other known monomersIproviding reactive oxy and carboxy groups such as mor p-hydroxybenzoicacid, 6- hydroxycaproic acid, or mixtures of terephthalic acid or itsmethyl ester with a glycol such as ethylene glycol in roughly a 1:1 molratio by following the same procedure illustrated above.

From the foregoing, it is readily apparent that we have provided new anduseful cumic acid compounds, polyester cumic acid monomers and valuablepolymers of the same together with the respective processes for theirproduction which are of significant value to the industry, the polymersbeing useful as heat resistant films or fibers and being characterizedby a high glass transition temperature.

Many modifications and variations of this invention will become apparentto those skilled in the art from the teaching herein and thus theinvention should be construed in the light of its spirit and scope usingthe appended claims as a guide thereto.

We claim: 1. A compound of the formula:

se if -ff-@C-M References Cited UNITED STATES PATENTS 3,221,060 1l/1965Albert 260--619 LORRAINE A. WEINBERGER, Primary Examiner E. J. GLEIMAN,-Assistant Examiner U.S. Cl. X.R. 260-473 R

